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Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (Linum usitatissimum).
Linseed oil is obtained by pressing, sometimes followed by solvent extraction.
Owing to its polymer-forming properties, linseed oil is often blended with combinations of other oils, resins, or solvents as an impregnator, drying oil finish, or varnish in wood finishing; as a pigment binder in oil paints; as a plasticizer and hardener in putty; and in the manufacture of linoleum.
CAS: 8001-26-1
EINECS: 232-278-6
Synonyms
OIL OF LINSEED;aceitedelinaza;Flaxoil;groco;huiledelin;LINUM USITATISSIMUM (LINSEED) SEED OIL;LINSEED OIL INSECT CELL CULTURE TESTED;LINSEED(FLAXSEED)OIL, 1000MG, NEAT
Linseed oil use has declined since the 1950s with increased availability of synthetic alkyd resins, which function similarly, are petroleum-based, and resist yellowing.
Linseed oil is an pale yellow oil extracted from the seeds of flax (linseed).
Linseed oil hardens on exposure to air (it is a drying oil) because it contains linoleic acid and linolenic acid, and is used in enamels, oilpaints, putty, linoleum and varnishes.
Linseed oil, with the CAS number 8001-26-1, is a pale yellow to amber-colored oil derived from the seeds of the flax plant (Linum usitatissimum).
Linseed oil is primarily composed of triglycerides, with a high content of polyunsaturated fatty acids, particularly alpha-linolenic acid, which is an omega-3 fatty acid.
Linseed oil is known for its drying properties, making it a popular choice in the production of paints, varnishes, and inks, as it can polymerize upon exposure to air, forming a solid film.
Additionally, Linseed oil is used in the food industry as a nutritional supplement and in the production of linoleum flooring.
Linseed oil has a characteristic nutty flavor and is rich in essential fatty acids, contributing to its health benefits.
However, Linseed oil is sensitive to heat and light, which can lead to oxidation and rancidity.
Proper storage in a cool, dark place is essential to maintain its quality.
Overall, linseed oil is valued for its versatility in both industrial and culinary applications.
Linseed oil, also known as flaxseed oil or flax oil, is a colourless to yellowish oil obtained from the dried, ripened seeds of the flax plant (Linum usitatissimum).
The oil is obtained by pressing, sometimes followed by solvent extraction.
Linseed oil is a drying oil, meaning it can polymerize into a solid form.
Structure and composition
Linseed oil is a triglyceride, like other fats.
Linseed oil is distinctive for its unusually large amount of α-linolenic acid, which oxidises in air.
The fatty acids in a typical linseed oil are of the following types:
The triply unsaturated α-linolenic acid (51.9–55.2%),
The saturated acids palmitic acid (about 7%) and stearic acid (3.4–4.6%),
The monounsaturated oleic acid (18.5–22.6%),
The doubly unsaturated linoleic acid (14.2–17%).
Linseed oil Chemical Properties
Melting point: -24.0℃
Boiling point: >316 °C
density: 0.93 g/mL at 25 °C(lit.)
refractive index: n20/D 1.4795(lit.)
Fp: >230 °F
storage temp.: room temp
Odor: bland
Dielectric constant: 3.2-3.5（0.0℃）
Stability: Stable, but polymerizes gradually upon exposure to air. Combustible. Incompatible with strong oxidizing agents.
Reacts violently with chlorine.
Material such as rags impregnated with linseed oil may spontaneously combust after a long induction period due to gradual exothermic reaction with oxygen.
Major Application: pharmaceutical (small molecule)
Cosmetics Ingredients Functions: PERFUMING
SKIN CONDITIONING
ANTIOXIDANT
SKIN PROTECTING
VISCOSITY CONTROLLING
ABRASIVE
ABSORBENT
BULKING
Cosmetic Ingredient Review (CIR): Linseed oil (8001-26-1)
EPA Substance Registry System: Linseed oil (8001-26-1)
Also known as flaxseed oil, linseed oil is golden yellow, amber, or brown drying oil with a peculiar odor and bland taste.
Iodine value 177, saponification value 189-195, acid number(max.) 4 (ASTMD 234-48), polymerizes on exposure to air.
Soluble in ether, chloroform, carbon disulfide, and turpentine; slightly soluble in alcohol, spontaneous heating.
Combustible.
Chief constituents are glycerides of linolenic, oleic, linoleic, and saturated fatty acids.
The drying property is due to the linoleic and linolenic groups.
Derivation is from seeds of the flax plant Linum usitatissimum by expression or solvent extraction.
Various refining and bleaching methods are used.
The grades of linseed oil are raw; boiled, double-boiled, blown, varnish makers' and refilled.
Linseed oil is currently one of the highest known vegetable oils with the highest content of essential fatty acids (omega-3 and omega-6 fatty acids).
Used in paints, varnishes, oilcloth, putty, printing inks, core oils, linings, and packings, alkyd resins, soap, and pharmaceuticals.
Drying properties
Having a high content of di- and tri-unsaturated esters, linseed oil is susceptible to polymerization reactions upon exposure to oxygen in air.
This polymerization, which is called autoxidation, results in the rigidification of the material.
To prevent premature drying, linseed oil-based products (oil paints, putty) are stored in airtight containers.
Rags soaked with linseed oil pose a fire hazard because they provide a large surface area for rapid oxidation.
The oxidation of linseed oil is exothermic, which may lead to spontaneous combustion.
In 1991, One Meridian Plaza, in Philadelphia, was severely damaged in a fire, in which three firefighters perished, thought to be caused by rags soaked with linseed oil.
Uses
The botanical properties of linseed oil are listed as emollient, antiinflammatory, and healing.
Derived from the flax plant seed, the oil is obtained by expression with little or no heat.
Linseed oil is a drying oil, meaning it can oxidise into a solid form. Due to this property, linseed oil is used on its own or blended with other oils, resins, and solvents as an impregnator and varnish in wood finishing, as a pigment binder in oil paints, as a plasticizer and hardener in putty, and in the manufacture of linoleum.
Linseed oil is still widely used for the finishing and refinishing of furniture and timber products.
Applications
Most applications of linseed oil exploit its drying properties, i.e., the initial material is liquid or at least pliable and the aged material is rigid but not brittle.
The water-repelling (hydrophobic) nature of the resulting hydrocarbon-based material is advantageous.
Paint binder
Linseed oil is the carrier used in oil paint.
Linseed oil can also be used as a painting medium, making oil paints more fluid, transparent and glossy.
Linseed oil is available in varieties such as cold-pressed, alkali-refined, sun-bleached, sun-thickened, and polymerised (stand oil).
The introduction of linseed oil was a significant advance in the technology of oil painting.
Putty
Traditional glazing putty, consisting of a paste of chalk powder and linseed oil, is a sealant for glass windows that hardens within a few weeks of application and can then be painted over.
The durability of putty is owed to the drying properties of linseed oil.
Wood finish
When used as a wood finish, linseed oil dries slowly and shrinks little upon hardening.
A linseed oil finish is easily scratched and liquid water penetrates a linseed oil finish in mere minutes, and water vapour bypasses it almost completely.
Garden furniture treated with linseed oil may develop mildew.
Oiled wood may be yellowish and is likely to darken with age.
Even though the oil feels dry to the touch, studies show linseed oil does not fully cure.
Linseed oil is a common finish for wooden items, though very fine finish may require months to obtain.
Studies show the fatty-acid structure of linseed oil has problems cross-linking and oxidizing, frequently turning black.
Gilding
Boiled linseed oil is used as sizing in traditional oil gilding to adhere sheets of gold leaf to a substrate (parchment, canvas, Armenian bole, etc.).
It has a much longer working time than water-based size and gives a firm smooth surface that is adhesive enough in the first 12–24 hours after application to cause the gold to attach firmly to the intended surface.
Linoleum
Linseed oil is used to bind wood dust, cork particles, and related materials in the manufacture of the floor covering linoleum.
After its invention in 1860 by Frederick Walton, linoleum, or "lino" for short, was a common form of domestic and industrial floor covering from the 1870s until the 1970s, when it was largely replaced by PVC ("vinyl") floor coverings.
However, since the 1990s, linoleum is returning to favor, being considered more environmentally sound than PVC.
Linoleum has given its name to the printmaking technique linocut, in which a relief design is cut into the smooth surface and then inked and used to print an image.
The results are similar to those obtained by woodcut printing.
Reactivity Profile
LINSEED OIL react with acids to liberate heat.
Heat is also generated by interaction with caustic solutions.
Strong oxidizing acids may cause a vigorous reaction that is sufficiently exothermic to ignite the reaction products.
Flammable hydrogen is generated by mixing with alkali metals and hydrides.
React with oxygen in the air to harden.
Can react with air fast enough to cause ignition of near-by combustible material if the heat builds up in an unventilated space (called "spontaneous combustion" in oily rags).
